Biz on an A319 oe 320 is a cradle seat, a bit of extra leg room. I cannot remember if these flights give you a sandwich or something, BOG CLO there is only about 15 minutes between turning the seatbelt sign off and turning it back on again, so no time for any meaningful service.
There is no alcohol served in any classes on either AV or LA
I have only been on a A318 on AV once, they came from the defunct Mexicana but so far as I could tell they had AV interiors so I believe they have the same biz seats. Like I said I only flew one once.
Note unlike LA, AV has a biz class and therefore biz lounges pretty much everywhere. Even PEI has a couple of tables and a beer fridge in a tiny lounge.
Don't forget that BOG CLO leaves from Avianca's Puente Aéreo and not from the main terminal. You'd be surprised how many people miss their flights by going to the wrong "airport." Puente Aéreo has a nice large biz lounge too.